1. Field of the Invention
The present invention pertains to the wireless pairing of electronic peripheral devices to a base unit device using a wireless protocol such as, without limitation, Bluetooth®, and, in particular, to a method of automatically wirelessly pairing one or more electronic peripheral devices to a base unit based on a signal measured at the base unit and a signal measured at the peripheral devices, for example using correlation analysis of the signals. The concept disclosed herein may be used in any application where a base unit has a sensor that would be expected to show some correlation to a sensor in a peripheral device that will wirelessly connect to the base unit and wherein a simple automatic pairing technique (not employing the concepts of the present invention) may be confused by having multiple peripherals. Such applications may include, without limitation, a positive pressure support therapy system including a base therapy unit and a mask having a peripheral component, such as a wireless pressure sensor, in order to automatically pair the peripheral component with the base unit without confusion. Other possible, alternative applications are described elsewhere herein.
2. Description of the Related Art
Many individuals suffer from disordered breathing during sleep. Sleep apnea is a common example of such sleep disordered breathing suffered by millions of people throughout the world. One type of sleep apnea is obstructive sleep apnea (OSA), which is a condition in which sleep is repeatedly interrupted by an inability to breathe due to an obstruction of the airway; typically the upper airway or pharyngeal area. Obstruction of the airway is generally believed to be due, at least in part, to a general relaxation of the muscles which stabilize the upper airway segment, thereby allowing the tissues to collapse the airway. Another type of sleep apnea syndrome is a central apnea, which is a cessation of respiration due to the absence of respiratory signals from the brain's respiratory center. An apnea condition, whether obstructive, central, or mixed, which is a combination of obstructive and central, is defined as the complete or near cessation of breathing, for example a 90% or greater reduction in peak respiratory airflow.
Those afflicted with sleep apnea experience sleep fragmentation and complete or nearly complete cessation of ventilation intermittently during sleep with potentially severe degrees of oxyhemoglobin desaturation. These symptoms may be translated clinically into extreme daytime sleepiness, cardiac arrhythmias, pulmonary-artery hypertension, congestive heart failure and/or cognitive dysfunction. Other consequences of sleep apnea include right ventricular dysfunction, carbon dioxide retention during wakefulness, as well as during sleep, and continuous reduced arterial oxygen tension. Sleep apnea sufferers may be at risk for excessive mortality from these factors as well as by an elevated risk for accidents while driving and/or operating potentially dangerous equipment.
Even if a patient does not suffer from a complete or nearly complete obstruction of the airway, it is also known that adverse effects, such as arousals from sleep, can occur where there is only a partial obstruction of the airway. Partial obstruction of the airway typically results in shallow breathing referred to as a hypopnea. A hypopnea is typically defined as a 50% or greater reduction in the peak respiratory airflow. Other types of sleep disordered breathing include, without limitation, upper airway resistance syndrome (UARS) and vibration of the airway, such as vibration of the pharyngeal wall, commonly referred to as snoring.
It is well known to treat sleep disordered breathing by applying a continuous positive air pressure (CPAP) to the patient's airway. This positive pressure effectively “splints” the airway, thereby maintaining an open passage to the lungs. It is also known to provide a positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient's breathing cycle, or varies with the patient's breathing effort, to increase the comfort to the patient. This pressure support technique is referred to as bi-level pressure support, in which the inspiratory positive airway pressure (IPAP) delivered to the patient is higher than the expiratory positive airway pressure (EPAP). It is further known to provide a positive pressure therapy in which the pressure is automatically adjusted based on the detected conditions of the patient, such as whether the patient is experiencing an apnea and/or hypopnea. This pressure support technique is referred to as an auto-titration type of pressure support, because the pressure support device seeks to provide a pressure to the patient that is only as high as necessary to treat the disordered breathing.
Pressure support therapies as just described involve the placement of a patient interface device including a mask component having a soft, flexible sealing cushion on the face of a patient. The mask component may be, without limitation, a nasal mask that covers the patient's nose, a nasal/oral mask that covers the patient's nose and mouth, or a full face mask that covers the patient's face. Such patient interface devices may also employ other patient contacting components, such as forehead supports, cheek pads and chin pads. The patient interface device is connected to a gas delivery tube or conduit and interfaces the pressure support device with the airway of the patient, so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient.
Pressure support therapy systems can be used with one or more peripheral electronic devices that may require data transfer between the peripheral electronic device(s) and the base pressure generating device. For example, and without limitation, it is known to provide a wireless pressure sensor in a mask component of a pressure support therapy system, wherein the wireless pressure sensor is structured to wirelessly communicate pressure information measured by the sensor to the base pressure generating device using a short range wireless communications/data transfer protocol such as, without limitation, the Bluetooth® protocol. Wireless communications/data transfer protocols are desirable and becoming less costly. Wireless data transfer protocols, especially Bluetooth®, typically require pairing between the two devices in question. As is known, such pairing typically requires user intervention.
While automatic pairing is technically feasible, methods to circumvent spurious pairing, for example between a base unit and peripherals that are not in use or between a base unit and peripherals that are in use but with another base unit (e.g. in a sleep lab environment or a home environment having multiple base units) are not adequately addressed in the prior art. Typical cases require the manual selection of a specific peripheral amongst a list of discovered peripherals. Such an environment 1 (e.g. in a sleep lab environment or a home environment having multiple base units) is shown schematically in FIG. 1. As seen in FIG. 1, environment 1 includes two pressure generating device base units 2 and 4, wherein pressure generating device base unit 2 is associated with mask 6 having peripheral device (e.g., wireless pressure sensor) 8 and pressure generating device base unit 4 is associated with mask 10 having peripheral device (e.g., wireless pressure sensor) 12. Thus, in environment 1, the two pressure generating device base units 2 and 4 are in proximity with the two peripheral devices 8 and 12, and both peripherals support wireless communication and are in use. Peripheral device 8 should be paired with pressure generating device base unit 2 and peripheral device 12 should be paired with pressure generating device base unit 4. However, there is no completely automated pairing solution available for this use case in the prior art. For example, a “just works” Secure Simple Pairing protocol may still require user intervention on the base unit, requiring selecting a given peripheral amongst a list of peripherals and having a unique code for a user to find and match amongst the list of peripherals.